Sandy, sorry your books were destroyed, from the Keller book, page 155 is this about the 30BP4 ltb/conversion:
“A last-time build of 500 tubes was made for replacment purposes and the 30BP4 was discontinued after only one to two years of production. A conversation kit to allow replacement with a 27-inch rectangular glass picture tube was produced to allow future replacements to be made.”
Footnoted to a interview with John McQueen, June 1989.
Photo of Mr. McQueen, from page 157:
jr